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Medical Marijuana Cards Are Sold Like Ice Cream at the Venice Beach Boardwalk

Here in California, marijuana is now treated as a minimal vice, with legalization inevitable and decriminalization for possession amounting to a tap on the hand. Medical marijuana cards are so easy to obtain, they're the butts of endless popular jokes.

On the famed Venice Beach boardwalk, booths tout on-the-spot "evaluations" and customers walk out the door with newly minted photo ID cards in under an hour. High schools across the country celebrate April 20th as "420 Day", a fact I know because my daughter's high school, San Rafael High, is nationally famous (or infamous, depending on your perspective) as the birthplace of the term 420. (Coined, supposedly, because 4:20 pm was the time at which kids would meet after school to light up.)

So, as we move towards viewing pot with the same tolerance with which we view alcohol (in other words, it's bad for your health if you become addicted, but casual use is harmless), let's look at the evidence. Is it really relatively harmless for young men -- and women -- to get high?

Today's headline was pretty bold: Smoking pot leads to double the risk of developing testicular cancer. Testicular cancer is on the rise, and experts have been trying for awhile to figure out why. Now, after comparing groups of young men who smoked and those who didn't, there's a possible answer. Those who smoked pot recreationally were twice as likely to develop testicular germ cell tumors, or nonseminomas, the most common kind in men under 35, says a study in Cancer. Nonseminomas are faster growing and harder to treat - a deadly combination - say researchers at the University of Southern California.

This study, though small, is actually the third study to link nonseminomas to pot use; the first two were also published in Cancer. The first word of the connection came out in 2009 from research out of the Fred Hutchinson Cancer Center in Seattle. The pot use researchers studied was described as "once a week or more", and it's important to note that many smokers toke up every day. No studies have contradicted the link, experts point out. It's important to note that the risk of testicular cancer is relatively low, slightly more than 1 percent, so even when the risk is doubled, it's still extremely small.

Pot Smoking May Lower IQ

Last week's headline was at least as alarming as this week's. Researchers followed a group of youngsters from age 13 to age 38, and found that the IQs of regular pot smokers fell up to 8 points during the 25-year period, compared with the IQs of those who didn't smoke pot, which stayed the same. The study, published in the Proceedings of the National Academy of Sciences, also found an increase in memory and attention problems among those deemed marijuana-dependent.

Pot Smoking May Trigger Schizophrenia

There should have been headlines, "Marijuana May Make You Psychotic" at least a couple times over the past few years, but somehow the studies documenting this issue haven't gotten as much attention as you might expect. Maybe it's because this link is much harder to prove, which it is. That's because the association could work backward: Those who smoke pot could be self-medicating for symptoms of schizophrenia that hasn't become full-blown yet.

However, there have been several studies, and they've controlled for a backwards causation pretty well. In a German study that followed a group of teenagers for ten years, those who smoked pot at least 5 times were more than twice as likely to develop schizophrenia. The biggest and probably best known study followed 45,000 young men in Sweden starting when they enlisted in the military. As I reported in a previous article, synthetic marijuana, also known as "Spice", has also been linked to psychosis as well as to paranoia and violence.

Fifteen years later, those who smoked pot at least once were more than twice as likely to develop schizophrenia. A third study followed young men whose family genetic history predisposed them to develop schizophrenia. In these kids, who are considered to have a one in ten chance of developing schizophrenia, pot use doubled that risk to one in five.

Pot Smoking Lowers Fertility and Causes Genetic Damage

The health risks of marijuana for women are much less well known, as of yet. But what is known is that pot smoking decreases fertility for both men and women, and appears to have the potential for genetic damage to future children. Though a complex mechanism, cannabinoids -- the chemicals in cannabis -- affect the production of sperm and the ability of the sperm and egg to join together. The research on pot and testicular cancer has implicated the endocannabinoid system, which is the cellular network that reacts to cannabis, the active ingredient in pot. The endocannabinoid system also plays a central role in sperm production.

There's also been considerable research on the issue of marijuana use causing genetic mutations that are then passed on to children. Of course most folks under 20 aren't looking ahead to to the health of their future offspring -- or to the possibility of not being able to have said offspring -- so this health issue is less influential with teens and young adults. But it's something everyone should be paying more attention to.